Insulator and method of assembly



Sept. 17, 1935. G. A. MATTHEWS INSULATOR AND METHOD OF ASSEMBLY FiledFeb. 2, 1933 Patented Sept. 17, 1935 UNITE stares re n 2,014,441INSULATOR, ANDMETHOD 0F ASSEMBLY (George A. Matthews, Detroit, Mich.Application February 2, 1933, Serial No. tamer 3 Claims. (0119482)" Thepresent invention relates in general to insulators and is particularlyconcerned with the details of construction of insulator hardware andfittings, and a novel method of securing the fit- 5 ting to theinsulating medium.

In the prior art constructions, it has in the main, been the custom toutilize one of two'principal methods for securing caps, bases and otherfittings of metallic material to an insulating body of such material asporcelain, glass and the like. In one of these arrangements, the metalhardware is cemented. to the porcelain whereas in the other arrangementthe hardware is secured with the metal in direct contact with theinsulating onto the insulating medium, casting the insulating medium inthe fitting during the molding process, and by various other ways whichare well known in the art.

The arrangement wherein the metallic fitting is cemented to theinsulating medium has proved unsatisfactory due to the difference in thecoeificients of expansion between the metal and the insulating medium.This reaction to the changes of temperature causes the cement to crackand deteriorate, the result being that the'operating characteristics ofthe insulator are decreased to such an extent that it must either berepaired or replaced; Moreover, this arrangement is objectionable inthat the dehydration of the cement results in an inferior joint betweenthe insulating medium and the fitting.

' In the other arrangement wherein the metal is in direct contact withthe insulating medium,

the different coefficients of expansion of the metal and insulatingsubstance is apt to cause cracking of the insulator or loosening of thejoint. Further, it has been found to be very difiicult to shrink themetal aboutthe insulating 40 a medium and form a tight joint, since theshrinking process is apt to result in damage to the insulatingsubstance. Moreover, the arrangement wherein the insulator ismolded intothe fitting is subject tn the same inherent disadvantages as in theother cases where the metal fitting is in direct contact with theinsulating medium.

With the foregoing in mind, the present invention seeks to overcome thedisadvantages of the prior art constructions, and to' this end proposesto secure the metal fitting to the insulating medium in such a mannerthat a substantially rigid joint will be attained, and which at the sametime will be sufliciently flexible to enable 55 the insulating mediumand the metallic fitting medium, either by clamping, shrinking the metalto individually respond to temperature changes withoutimpairing thejoint between the insulating medium and the metallic fitting. v v It istherefore a principal object of the present invention to provide asimple and novel means 5,

whereby an insulating medium such as porcelain, glass and the like maybe secured to a metallic member.

It is a further object of the present invention to provide improvedmeans for joining a metallic 10 member and insulating medium such asglass, porcelain and the like, which are so constructed and designed asto form a fluid tight joint therebetween. It is a further object of theinvention to provide an improved support for an insulating 15 body andnovel connecting means for connecting the insulating body and support insuch a manner as to form a flexible and-fluid tight joint therebetween.v

It is a still further object of the invention to 20 provide an improvedmethod for securing a metallic fitting to an insulating medium of glass,porcelain and the like.

V In accordance with the general features of this invention, it isproposed to provide an in- 5 sulating medium of porcelain, glass and thelike having a portion which is substantially cylindrical in shape. Thesurface of this portion is grooved or otherwise roughened and surroundedwith a layer of resilient material such as rubber. 0 The fitting isconstructed with a band or collar portion which is placed around theresilient material, after which the band or collar '18 spun or rolled soas to conform to the grooves or other irregularities in the surface ofthe cylindrical portion of the insulating medium. rolling or spinning ofthe metal causes the resilient layer to also conform to theirregularities of this surface and seal the space between the metal andI the insulating medium, whereby a substantially rigid andfluid tightjoint is attained between the metal and the insulating medium, theresilent layer of material enabling the insulating medium and metal tophysically respond to changes" in temperature without impairing thejoint therebetween.

Other objects and features of this invention willmore fully appear fromthe following detailed description taken in connection with theaccompanying drawing which illustrates a single embodiment thereof, andin which:

Figure 1 is an enlarged elevation partly in section of an insulatorassembly embodvin he present invention; and

Figures 2 and 3 illustrate different steps in the 55 method of securinga metallic fitting to an insulating medium in accordance with thisinvention.

As shown on the drawing:

As illustrative of the present invention, there is disclosed in Figure 1an insulator assembly which embodies the features of the invention. Thisinsulator assembly comprises an elongated body- ID of insulatingmaterial such as porcelain, glass and -the like, which in this instancehas a central opening II to enable a conductor to be carriedtherethrough. Although the invention is shown in connection with ahollow cylindrical insulating body, it will be apparent to those skilledin the art that it may with equal facility be applied to a solidinsulating body such as maybe used in connection with a bus support andthe like.

The insulating body I!) is formed adjacent its lower end with acylindrical portion l3 which is circumferentially grooved adjacent itsend extremities as shown at M.

The insulating body is supportedby means of a bracket fitting generallyindicated by the numeral I5. This fitting comprises a sleeve portion l6which is disposed circumferentially around the cylindrical portion l3 ofthe insulating body and terminates at its upper end in an outwardlyextending flange IT and at its lower end in an outwardly extendingflange l8. Intermediate the flanges l1 and I8, the sleeve I6 is providedwith circumferentially extending grooves l9 which are so positioned asto overlie and be in registration with the grooves M of the cylindricalportion [3 of the insulating body.

The sleeve I6 of this supporting bracket, it will be observed, is not indirect contact with the cylindrical portion of the insulating body butin cushioned thereon by means of circumferentially extending gasketswhich are disposed between the grooved portions of the sleeve and thegrooved portions of the insulating body, the grooves of the sleevecompressing these gaskets into the grooves of the insulating body.Although the drawing discloses an individual gasket for each groove, itwill be apparent that a single sleeve of elastic material such as rubberand the like may be disposed around the cylindrical portion of theinsulating body between this portion and the metallic sleeve. It will beapparent that this arrangement interlocks the metallic fitting to theinsulating body and produces a substantially rigid joint therebetweenwhich is fluid tight, thereby enabling this arrangement to beeifectively used where the joint is to be submitted to fluid pressure.

The downward thrust of the above described insulating body isadditionally resisted by the flanged portion ll of the sleeve of thefitting, this flange being in engagement with a resilient gasket 2|which is disposed between the flange I1 and the lowermost petticoat ofthe insulating body.

The annular flange l8 may be provided with a plurality of apertures forreceiving therethrough bolts 22 for securing the fitting to a supportingstructure such as shown at 23.

From the above description, it will be apparent that fittings for theupper end of the insulating body may be secured thereto in the samemanner as just described in connection with the supporting bracket. Theupper end of the insulator is similarly provided with a cylindricalportion 24 which is circumferentially grooved as shown at 25. In thisparticular instance, a terminal connection generally indicated at 2B isshown as being secured at the upper end of the insulating body. Thisfitting includes a cap portion 21 which is adapted to fit over the endof the insulating body and embrace the circumferentially grooved por- 0tion 24. This cap is circumferentially grooved as shown at 28 inthe-same manner as in the case of the sleeve l6 previously described,the cap grooves and the grooves of the insulating body being separatedby gaskets of resilient material as shown 10 at 29. It has also beenfound desirable to provide a resilient gasket 30 between the upper endof the insulating body and the top portion of the cap.

It will be apparent that, although inwardly ex- 15 tending grooves aredisclosed on the insulating body and the metallic fittings, any numberof grooves maybe used and that these grooves may be of any desiredshape, and further, that the grooves may extend outwardly rather thaninwardly, the purpose of these grooves being to in terlock the metallicfittings and the insulating body against axial relative movement, exceptinsofar as flexibility is permitted by the resilient gasket. While theinvention in its broad aspectcontemplates that these grooves may be ofany desired shape, it' is preferable that the grooves of both theinsulating medium and the metallic fitting 0 shall be of such shape asto not be readily affected by changes in temperature of the mediumcontaining the grooves. Moreover, the grooves in the metallic fittingsand the grooves in the insulating medium are preferably disposedrelative to each other in such a manner that ii any expansion shouldoccur in one relative to the other, the joint will not be impaired andthe insulating medium and metallic fitting are free to respondindividually. 40

It will also be apparent that, where the insulating medium is to be usedin connection with a container having a liquid such as oil therein, thelower end of the fitting may be formed so as to extend past thelowermost gasket and cooperate r with the insulating medium to form anair pocket or space as shown at 29a. Should the liquid in the containerrise to such an extent as to reach the lowermost gasket, air will beentrapped in the space 29a and prevent the liquid from com- 0 ing incontact with the gasket.

The method of assembling the insulating body and fittings, and themanner in which a fitting is secured to the insulating body will be morefully understood by reference to Figures 2 and 3.

It is thought that the description of the method of securing the capfitting to the insulating body will be sufficient to enable the methodto be practiced in securing other fittings to the insulating body. It istherefore not deemed necessary to describe the method in connection withthe supporting bracket.

The fitting 26 as previously described is provided with a cap portion,this portion initially being a plain surface without grooves therein as5 shown in Figure 2. The fitting is inserted over the end of theinsulating body with the side portion 21 extending over the grooves 25and with the resilient gaskets disposed between the metal and insulatingbody.

A mandrel 3! as shown in Figure 3 is inserted within the insulating bodyin order that the body and fitting may be revolved together. The metalcomprising the side portion of the fitting is then spun or rolled by atool as indicated at 32, this tool being so formed as to produce thecircumferential grooves in the metal'during the working operation.

It will be observed, as shown in Figure 3 that as the spinning operationprogresses, the metal is pushed into the grooves in the insulating bodyand the resilient gaskets are, moreover tightly compressed between themetal and the insulating material. In this manner, a substantially rigidinsulating medium such as porcelain or glass may be secured to ametallic fitting; which is so constructed and designed as to form afluid tight joint, which enables the insulating medium and metallicfitting to individually respond to temperature changes without impairingthe joint therebetween; and an improved method for securing the metallicfitting to an insulating medium.

Now, it is of course to be understood that although I have described indetail the preferred embodiment of my invention, the invention is not tobe thus limited only insofar as defined by the scope and spirit of theappended claims.

I claim as my invention:

1. In the method of supporting a porcelain insulator and in assemblingsaid insulator with a metallic support to make said metallic supportsubstantially integral with said insulator but in spaced and fluid tightrelation to the porcelain thereof, the steps of providing an elongatedcylindrical portion of said porcelain insulator with an irregularsurface, placing a layer of an elastic material, such as rubber, oversaid irregular surface, telescoping a cylindrical metallic sleeve havinga pair of outwardly extending terminal flanges over said layer. ofelastic material, spinning the metal of the sleeve to cause it and thelayer of elastic material to substantially conform to the surface ofsaid cylindrical portion of said insulator and thereby make said sleevea substantially integral part of said insulator, and securing one ofsaid flanges to a support to thereby support the assembled insulator andsleeve as a unit.

2. In the method of forming a porcelain insulator and a metallic supporttherefor into a single unitary structure by making the support asubstantially integral part of the insulator but in spaced and fluidtight relation thereto, the steps of providing an elongated andcylindrical portion of said porcelain insulator with an irregular sur=in face, placing a layer of an elastic material, such as rubber, oversaid irregular surface, providing an outstanding annular boss on saidinsulator, telescoping a metallic bobbin having upper and loweroutstanding terminal flanges over said layer 15 of elastic material,placing a gasket of non-metallic material between the upper flange ofsaid bobbin and said outstanding boss, spinning the metal of said bobbinto cause it and the layer of elastic material to substantially conformto the surface 20 of said cylindrical portion and make said bobbin anintegral part of said insulator and whereby the resulting unitarystructure is supportable as a unit by resting only said lower flange ona support. 26

3. The method of connecting a metallic supporting member to a porcelaininsulator through an elastic bond whereby said metallic member is madesubstantially integral with said insulator and whereby the resultingunitary structure is 30 adapted for support as a unit by securing onlysaid metallic member to suitable external supporting means, said methodcomprising providing a cylindrical portion of said porcelain insulatorwith an irregular surface, placing a layer of an elastic material, suchas rubber, over said roughened surface, telescoping a metallic sleeveover said layer of elastic material, spinning the metal of said metallicsleeve to cause it and the layer of elastic material to substantiallyconform to the surface of said cylindrical portion and make said sleevean integral part of said insulator, and providing said sleeve with anintegral outstanding member whereby said insulator and sleeve areadapted to be supported as a unit when only said outstanding member issecured to external supporting means.

- GEORGE A. MATTHEWS.

